1. Field of the Invention
The present invention relates to a method of carrying .gamma.-alumina by a porous ceramics structure. More specifically, the invention is concerned with a method for carrying .gamma.-alumina by a porous ceramics structure which is used as a catalyst carrier in an exhaust gas cleaning device for an automotive internal combustion engine or as a fine-particle trapping carrier for trapping fine carbon particles in the exhaust gas from an automotive internal combustion engine.
2. Description of the Prior Art
In a typical conventional method for carrying .gamma.-alumina by porous ceramics structure, the porous ceramics structure is immersed in a colloidal ceramics slurry containing alumina. The ceramics structure is then dried and fired so that the .gamma.-alumina is carried by the skeletal surfaces of the porous ceramics structure.
According to this conventional method, the .gamma.-alumina is carried on the skeletal surface of the porous ceramics structure in the form of a plain thick layer, so that the skeletal surface becomes too smooth to improve the contact between the .gamma.-alumina and a gas to be treated.